Dampness in the basement on the floor slab and walls

Thank you very much for the helpful addition

And what do you estimate something like that would cost? And won't the material (foundation slab, wall) be permanently damaged because water will still get there?

The concrete floor slab does not care at all that it is permanently damp. The stones don’t either. It is only critical if the moisture permanently seeps into the basement room. Then there will be more and more flaking, etc.

The sealing slurry costs about 3-4€/kg, you need about 4 kg per m2. Depending on the need, cement mortar 100-200€ and small items like measuring trowels 50€ and sealing tape also 100€. So manageable.

So if it were that easy, everyone with a wet house would do it ... what are the disadvantages?

"It only works this simply if the moisture is rising moisture coming through the floor slab and a horizontal barrier in the masonry is present.

In the case of defective or insufficient sealing of the basement walls in the soil, a comparable approach is indeed possible, but not always effective - because the permanently damp walls also release moisture again at the boundary between the soil and the surface, even with internal sealing, causing the plaster to peel off here, which leads to consequential damage. Furthermore, without a horizontal barrier, the moisture in the walls can also continue to rise into the living areas on the ground floor - which is significantly worse than in the basement.

In the case of defective sealing of the walls, work must therefore be done from the outside. This is sometimes significantly more complex and of course also more expensive. Incidentally, the material costs (without additional insulation) are hardly higher, but the labor effort due to earthworks is significantly greater.

Before such extensive earthworks in existing buildings, it is advisable to clean existing drainage systems or repair them if present and to check all rainwater pipes for tightness."

Hello everyone, I have to get back to my thread again. I now plan to seal the basement accordingly over the autumn/winter, when the weather is too bad to work outside. Our hardware store has an offer, but I am not sure if it is the product that is needed.